the noctura's look nice but at twice the price of everything else I think i could live with a bit more noise to save some moneyEm just my 2 cents the Scythe Ultra Kaze 120mm 2000 rpm fan's to replace existing fan's for less noise might not be the best for a low noise application. Some might say you can put it on a fan control and make them less quiet but whats the point of that your then not getting the full benefit of the fan.
Get the Noctua Nf-p12s
Or i know some might not agree but the Thermaltake 120mm fans are also awesome as well verry quiet im still using the two that came with my Matrix case one blue one on the front of my hard drive cage and one cooling down my Video card. They add no noise to my application i run 6 Noctuas Nf-P12s and 2 Thermaltakes 1 Antec Spot cool and 1 Asus mini fan i must say the computer has gotten even more silent since i changed from my Asus A8n-sli deluxe it had a motherboard fan spinning at 6000 rpm which was the loudest thing in my computer lol i know wackkk.
Anyways if you cannn spend the money get sum Noctua;s if not the Thermaltakes or something more in that line i personally wanted silence or close to it and thats what i got i didnt mind spending the extra money but if your going watercooling i wanted to eliminate sound so to me this was the point of it.
Btw i use the Mushkin Ascent Redline 8000 4gb kit which i got for 130 with the 30 rebate comes to 100 i havent really clocked it to its full potential but i got it to 1055 but i dont think it will make a difference going so high im sure someone with more experience can elaborate on that.